A. Field of the Invention
The present invention relates to container tanks used in vehicles such as cars, trucks, planes and boats to contain liquids such as water or fuel, which are to be consumed in transit or delivered by the vehicle. More particularly, the invention relates to devices for decreasing the amplitude and duration of fluid oscillations, i.e., sloshings, of a liquid in a tank, which are induced in response to movements of a vehicle in which the tank is mounted.
B. Description of Background Art
Oscillations of a liquid such as water or fuel contained in a tank mounted in a vehicle such as a car, truck, plane or boat are induced in response to inertial accelerations of the vehicle. The natural or resonant frequency of such oscillations is an inverse function of the internal dimensions of the tank and depends to a lesser extent, upon properties of the liquid such as density and viscosity. Liquid oscillations can produce sloshing sounds which are annoying to people close to a tank, as for example, in smaller boats and personal watercraft. Moreover, in some cases, large values of linear momentum can be transferred to a tank and tank support structure as a result of oscillations of liquid contents of the tank. Such oscillations, or sloshing, can result in fatigue wear and ultimate failure of the tank mounts, and support structure. Even worse, in extreme cases, oscillations of liquid in a vehicle-mounted tank can become so large as to result in loss of steering control and even roll-over of the vehicle. Accordingly, it would be desirable to provide an effective means for damping or attenuating oscillations of fluids within tanks. One method for limiting large scale oscillations of a liquid in a tank consists of partitioning the interior of the tank into a plurality of individual cells which communicate with one another, such as by providing a plurality of baffle members within the tank interior. With this arrangement, energy of oscillating liquid in the tank is dissipated by frictional contact of the liquid with edges of intruding baffle members and/or passageways provided through the baffle members.
Another method for damping fluid oscillations in a tank consists of inserting into the tank through a fill port a plurality of small, hollow spheroidal shell-shaped objects made of a fluid resistant polymer. The spheroidal shells have four relatively large holes formed therethrough, including a first pair of diametrically opposed holes centered on North and South poles of the sphere, and a second pair of diametrically opposed holes centered on equatorial antipodes of the spherical shell. The devices apparently work by converting linear momentum of oscillating fluid within the tank to angular momentum of the devices and vortices within the fluid. Ultimately, dissipative viscous forces between the vortices and surrounding fluid within the tank dissipate the oscillation energy.
A wide variety of other techniques have been disclosed which are intended to dampen to smaller amplitudes and durations undesirable, potentially damaging fluid oscillations or sloshing of liquids contained in tanks mounted on moving vehicles. References disclosing such techniques include:    Conway et al., U.S. Pat. No. 3,400,854, Sep. 10, 1965, Anti-Slosh Media For Fuel Tanks;    Conway et al., U.S. Pat. No. 3,349,953, Oct. 31, 1967, Anti-Slosh Media For Fuel Tanks;    Evensen et al., U.S. Pat. No. 3,443,584, May 13, 1969, Buoyant Anti-Slosh System;    Pollack, U.S. Pat. No. 3,784,050, Jan. 8, 1974, Floating Baffle System For Fuel Tanks;    Stedman et al, U.S. Pat. No. 4,764,408, Aug. 16, 1988, Foam Plastic Baffle For Fluid Containers;    Sasaki et al., U.S. Pat. No. 4,974,743, Dec. 4, 1990, Fuel Tank With Noise Suppressing Arrangement;    Spickelmire, U.S. Pat. No. 5,890,618, Apr. 6, 1999, Liquid Stabilizing Baffle System;    Behr et al., U.S. Pat. No. 6,032,347, Mar. 7, 2000, Tank And Manufacturing Method For The Same;    Evans, U.S. Pat. No. 6,062,417, May 16, 2000, Liquid Storage Tank And Baffle System;    Fenton et al., U.S. Pat. No. 6,415,942, Jul. 9, 2002, Filler Assembly For Automobile Fuel Tank;    Spickelmire et al., U.S. Pat. No. 6,547,090, Apr. 15, 2003, Liquid Stabilizing Baffle;    Bambacigno, U.S. Pat. No. 6,848,472, Feb. 1, 2005, Liquid Stabilizing Deflector Baffle;    Spickelmire et al, U.S. Patent Application No. US2002/0063133, May 30, 2002, Liquid Stabilizer;    Konja, U.S. Patent Application No. US2003/0015537, Jan. 23, 2003, Vehicle Fuel Tank With Fuel Wave Baffle;    Fenton, U.S. Patent Application No. US2004/0159663, Aug. 19, 2004, Fuel Tank And Filler Packet For Dispersing Ballistic Shock;    Krogull, U.S. Patent Application No. US2004/0173616, Sep. 9, 2004, Device For Reducing Sloshing Of Fuel In A Fuel Tank.
The present invention was conceived of to provide an anti-slosh device for damping oscillations of liquids contained in existing tanks of a wide variety of sizes and shapes.